1. Field of the Invention
The present invention relates generally to communication resource access in a communication system, and more particularly, to a resource access apparatus and method for peripheral devices and sensors that use short-range communication.
2. Description of the Related Art
Commonly used short-range communication includes technology such as BLUETOOTH® (hereinafter “Bluetooth”), Zigbee, Body Area Network (BAN), etc. Unlike cellular communication, short-range communication has difficulty implementing complicated Medium Access Control (MAC) algorithms. Therefore, it is important to design a system that is as simple as possible, but one that can attain its desired purposes. For example, BAN may implement a system that has a very small coverage area and which consumes an ultra-low amount of power.
Bluetooth basically uses Time Division Multiple Access (TDMA) that allocates time-divided slots to a master node and a plurality of slave nodes. One slot has a time interval length of 625 microseconds (μsec). Odd slots are allocated to the master node, and even slots are allocated to the slave nodes. In order to support the plurality of slave nodes, Bluetooth forms 79 1-MHz channels in a frequency band, and hops to other channels at every slot in order to reduce a collision probability between the slave nodes. However, due to the fact that frequent channel hopping increases power consumption, Bluetooth is unsuitable in a power-limited environment, such as sensors. When supporting a plurality of nodes having different traffic requirements, a fixed TDMA allocation scheme may generate empty slots. However, if a variable TDMA allocation scheme is used to reduce the empty slots, a control signal load may increase.
Zigbee provides a low-cost communication system for wireless access in an environment where limited power and low data rates are used. Zigbee provides TDMA-based Guaranteed Time Slot (GTS) and Carrier Sensing Multiple Access/Collision Avoidance (CSMA/CA) as its channel access scheme. GTS supplements the shortcoming of CSMA/CA and provides a Quality-of-Service (QoS) guarantee for real-time data traffic. However, Zigbee must undergo a GTS request process for a master node, and must provide information on the number of GTS allocation nodes and information on allocated slots at every super frame. When the number of slave nodes frequently changes, the slave nodes are different from each other in terms of required rates, or the slave nodes require variable rates rather than fixed rates, system performance by GTS allocation may decrease. CSMA/CA has superior extensibility regarding the number of nodes and a traffic load. However, CSMA/CA also has poor time resource efficiency because transmission is performed after a lapse of Inter Frame Spacing (IFS) and a waiting time of a predetermined number of slots when it senses (or listens to) transmissions of other nodes for collision prevention.
BAN is under standardization as an international standard, Institute of Electrical and Electronic Engineers (IEEE) 802.15.6 TG6 BAN. BAN may be used in the field of medical services, such as remote diagnosis within two meters from the human body over a communication network. Further, BAN may be used in the field of entertainment services that use wearable equipment or motion sensors for wearable computing. However, both TDMA and CSMA/CA fail to meet ultra-low power requirements while also supporting various services and ensuring adaptation to changes in environment.